Thinking About Mulching Your Lawn?
Mulch blades turn grass clippings into a free lawn feed. Here’s how they work, whether they’re worth it, and how to get the best results from mulch mowing.
Quick Answer: Mulch Blades Explained
Mulch mowing (also called “grasscycling”) is increasingly popular in the UK as gardeners realise they can skip the green bin and feed their lawn at the same time. The concept is simple: instead of collecting grass clippings, a mulch blade chops them so finely that they disappear into the turf and decompose within days. It’s essentially turning your mower into a fertiliser spreader.
How Mulch Blades Work
The key differences between mulch blades and standard mower blades:
Most modern rotary mowers can accept mulch blades, and many come with a “mulch plug” that blocks the discharge chute, keeping clippings circulating under the deck for longer. Check your mower’s manual to see if a mulch blade option is available for your model.
Benefits of Mulch Mowing
Mulch mowing offers several genuine advantages:
- Free fertiliser. Returning clippings to the lawn recycles up to 25% of the nitrogen your lawn needs annually. Combined with a spring lawn treatment, this can reduce your fertiliser costs significantly
- No green waste. Skip the collection box, the green bin and the trips to the tip. Mulch mowing eliminates grass clipping waste entirely
- Time saving. No stopping to empty the collector. Most gardeners find mulch mowing takes 20–30% less time than collect mowing
- Soil health. The fine organic matter feeds earthworms and soil bacteria, gradually building a healthier, more resilient turf
- Moisture retention. A thin layer of decomposing clippings helps the soil retain moisture during dry spells
When Mulch Blades Don’t Work Well
Mulch mowing isn’t perfect for every situation. It works poorly when:
- Grass is too long. If you’ve missed a couple of mows and the grass is over 8cm, a mulch blade can’t process the volume. The deck clogs, clippings dump in clumps, and the lawn looks messy. For overgrown lawns, collect first and mulch-mow once the lawn is back under control
- Grass is wet. Damp clippings clump together rather than dispersing into the turf. Mulch mowing is always best on dry grass
- Lawn has disease. If your lawn has fungal disease (red thread, fusarium), mulch mowing can spread the spores across the entire lawn. Collect and dispose of clippings until the disease is treated
- You want a pristine striped finish. Mulch mowing produces a slightly less defined stripe than collecting. For a show-quality lawn, collect during peak display months and mulch-mow at other times
How to Get the Best Results
- Follow the one-third rule. Never cut more than a third of the blade length. If your grass is 6cm, set the mower to 4cm. This keeps clippings small enough for effective mulching
- Mow regularly. Weekly mowing during the growing season (April–October) keeps growth manageable. Fortnightly mowing produces too much material for the blade to process
- Mow when dry. Wait for morning dew to dry before mowing. Wet clippings clump, clog the deck and sit on the lawn surface instead of filtering down
- Keep the blade sharp. A dull mulch blade tears grass rather than cutting it cleanly. Sharpen or replace blades at least once per season — more often for larger lawns
- Slow down slightly. Mulch blades need a fraction more time to process clippings. Walking slightly slower than usual gives the blade time to re-cut each piece thoroughly
- Vary your mowing pattern. Change direction each mow. This distributes clippings more evenly and prevents the grass developing a grain that lies in one direction
Do Mulch Blades Cause Thatch?
This is the most common concern about mulch mowing, and the answer is no — properly mulched clippings do not cause thatch build-up. Here’s why:
- Thatch is made of stems and roots, not leaf blades. Grass clippings are mostly water (80%+) and decompose within 1–2 weeks
- Finely chopped clippings decompose faster than whole leaves. The mulch blade’s multiple cuts accelerate the breakdown process
- Research confirms it. Multiple university studies have shown no increase in thatch from mulch mowing when the one-third rule is followed
If your lawn already has a thatch problem, mulch mowing won’t make it worse — but it won’t fix it either. Thatch requires mechanical scarification, which is a separate maintenance task. For a complete lawn care approach, combine mulch mowing with our spring lawn treatment and annual autumn scarification.
Mulch Blade Options for UK Mowers
Most popular UK mower brands offer mulch blade kits:
- Mulch plug kits: Many mowers come with a mulch plug that blocks the discharge chute. Install the plug, fit the mulch blade, and you’re set. Check your mower manual — some models include the plug as standard
- Aftermarket blades: If your mower doesn’t have a dedicated mulch option, aftermarket mulch blades are available for most models (£15–40). Ensure you match the blade length and centre hole size exactly
- Dedicated mulching mowers: Some mowers are designed specifically for mulching with a sealed deck, mulch blade and no collection option. These produce the finest results but lack versatility
Frequently Asked Questions
Can I switch between mulching and collecting?
Yes, most mowers allow you to swap between a mulch blade and standard blade, or simply add/remove the mulch plug. Many gardeners collect in spring when growth is rapid, then switch to mulching during summer when growth slows. This flexible approach gives you the best of both worlds.
Will mulch mowing make my lawn look messy?
Not if you follow the one-third rule and mow when dry. Properly mulched clippings are virtually invisible within a few hours. If you see clumps or visible clippings, you’re either cutting too much at once or mowing wet grass. Adjust your mowing height or frequency rather than switching back to collecting.
Do mulch blades work on all mower types?
Mulch blades are designed for rotary mowers only. Cylinder (reel) mowers use a different cutting mechanism and cannot accommodate mulch blades. If you use a cylinder mower for a fine lawn, you’ll need to continue collecting clippings. However, you can use those clippings as mulch in other parts of the garden.
How often should I sharpen mulch blades?
Sharpen mulch blades every 20–25 hours of mowing, or roughly every 2–3 months during the growing season for an average-sized UK lawn. A dull mulch blade is worse than a dull standard blade because torn grass doesn’t decompose as quickly and is more susceptible to disease. Balancing the blade after sharpening is important — an unbalanced blade causes vibration and uneven cutting.
Can mulch mowing replace lawn feed entirely?
Not entirely, but it reduces the need significantly. Mulch mowing returns roughly 25% of the nitrogen your lawn needs. For a healthy, green lawn, combine mulch mowing with one or two feeds per year — a spring treatment and optionally an autumn feed. This combination provides complete nutrition with less product and less cost.
What about mulching in garden beds?
Mulch blades are specifically for lawns. For garden beds, you need traditional mulch materials like bark, wood chip or compost applied by hand. The best mulch for weed prevention in beds is composted bark at 5–8cm depth — a completely different approach to the lawn mulching discussed here. You might also want to check how much mulch you’ll need for your beds.
You might also find it helpful to read about mow at the right frequency.
You might also find it helpful to read about common lawn care mistakes.
You might also find it helpful to read about identify common lawn weeds.
See also our guide on how often to top up mulch.
Give Your Lawn a Boost This Spring
Combine mulch mowing with a proper spring feed for the healthiest, greenest lawn on the street. Our spring treatment provides the nutrients that clippings alone can’t supply.
